A trio of extraordinary stone carvings found in Northumberland have got archaeologists and experts so baffled they've asked for help in deciphering them.

"We have enjoyed speculating about the meaning of these new and unusual markings," explained Dr Aron Mazel of Newcastle University’s School of Historical Studies, "but the truth is we really don’t know what they are."

The markings were found by Dr Mazel and international rock art expert, Stan Beckensall while they were charting the phenomenon of prehistoric rock markings in Northumberland.

Records and examples of over 950 traditional 'cup and ring' prehistoric rock art panels exist in Northumberland. These specimens typically feature a series of cups and concentric circles pecked into sandstone outcrops and boulders.

However, three unusual new markings found carved into rocks at separate locations are completely different from anything experts have seen before.

They consist of a small heart shape and a stylised carving of a human face, both found near prehistoric rock carvings close to Rothbury, and one discovered near Wark, which is such an unusual combination of lines and circles that it is impossible to say what it depicts.

Traditional 'cup and ring' marks are thought to have been made thousands of years ago by Neolithic and Early Bronze Age people.

However, it is believed that the newly-discovered mystery marks could be much younger, with the heart and the face shapes potentially as little as 100-250 years old.

"We found the heart marking next to a quarried edge, and I like to think it’s the work of a lonely quarryman," said Dr Mazel.

"The stylised face reminds me of works done by Picasso around a hundred years ago that were inspired by African totemic carvings, but an art historian may think otherwise. The other marking is just so unusual that we have no idea what it is."

The carving found near Wark has been shown to experts at the British Museum but they and the Newcastle University team have been so puzzled by it that they’ve issued an appeal for any information about what it is and what it might represent.

"We would welcome any suggestions from people who can offer a well-informed insight into who did the carvings and what they might represent," added Dr Mazel.

This isn’t the first time that Dr Mazel and Stan Beckensall have made an international appeal for help.

As reported on the 24 Hour Museum in October last year, the Northumberland Rock Art Project team sought an explanation for another set of mysterious markings hewn into an isolated sandstone boulder.

"It is likely that there are more unusual carvings out there," said Dr Mazel. "We have heard about a carving which resembles a Napoleonic soldier but we haven’t managed to locate it yet."

Mr Beckensall, who was recently awarded an honorary degree from Newcastle University for his contribution to archaeology, added:

"The carving found near Wark is the most dramatic and is unique. We thought it could have been an elaborate fossil remain but if you examine it carefully you can see it’s made by people - we don’t know how or when."

"I just hope that somebody who sees a picture of it has seen something like this before and can help solve our mystery."